Ray detection tube



y 1951 F. KCDURY RAY DETECTION TUBE 2 Sheets-Sheet 1 Filed June 30, 1948Frederic Koury INVENTOR.

ATTORNEY May 15, 1951 F. KOURY RAY DETECTION TUBE 2 Sheets-Sheet 2 FiledJune 30, 1948 o x I o w m w w w w w o o o o O 0 O o 8 7 6 5 4 3 2 l.

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Freder 6m. ATTORNEY Patented May 15, 1951 RAY DETECTION TUBE FredericKoury, Somerville, Mass, assignor to Sylvania Electric Products Inc.,Salem, Mass, a, corporation of Massachusetts Application June 30, 1948,Serial No. 36,090

11 Claims.

This invention relates to ray detection tubes, such as tubes of theGeiger-Mueller type, and particular y to tubes used for beta and gammarays, although the invention is not confined to such uses.

Such tubes generally comprise a cylindrical metal cathode surrounding awire anode in a gas.

An Object of the invention is to provide a rugged and inexpensive tubefor ray detection. This is achieved by making the cathode as an integralpart of the tube of glass or the like containing the device. The cathodeis a metal layer or layers directly bonded to the inner surface of theglass tube. The metal layer is preferably silver, bonded to the glass bya layer of silver oxide or the like, and covered by an additional layerof other and more ray-responsive metal, if desired. In some cases, andparticularly if a filling containing halogen vapors is used, this may becovered by a protective layer, for example, of; chromium, platinum,palladium, rhodiurn, iridium or chrome-iron.

Other objects, advantages and features of the invention will be apparentfrom the following specification and its accompanying drawings, inwhich:

Figure l is a perspective view, shown broken away and partly in section,of a beta-ray tube according to the invention;

Figure 2 is a perspective view, shown broken away and partly in sectionof a device according to the invention;

Figure 3 is a perspective view, shown broken away and partly in sectionof a gamma ray tube according to the invention; and

Figure 4 is a graph showing the response in counts per minute versusvoltage of a standard copper cathode tube and of a tube coated withsilver according to my invention. The latter curve is marked A.

In the figures, the glass tube i has on its interior surface a metallicsilver layer 3, held to the glass by the thin bonding layer 2 of silveroxide. This layer may be produced by the method described in mycopending application Serial No. 36,689, filed June 30, 1948, nowabandoned, for a High Voltage Condenser. The silver layer will be ofmetallic color, while the oxide layer will show through the glass as asort of straw-brown color. Where the tube is for beta rays, the silverlayer itself may be the final one, if desired, or may have a layer ofsome other metal over it lor example plated over it, if desired. Wherethe tube is for gamma rays, a coating 4 of bis- 2 muth may be platedover the silver layer, as for example in Figure 2, for high efficiency.

The metallic coatings may end a short distance from the end 5 of thetube through which the lead-in wires extend. The metallic coating willordinarily end some distance from the other end B in a gamma ray tubesuch as in Figure 3, for example, in order to allow room for anchoringthe support wire 7 to the end 8. In Figure 2, the lead-in wire 8 whichmay for example be of Kovar or other metal capable of being sealed tothe glass used, has the anode wire 9 welded or otherwise afixed thereto.The insulating tube it, for example or" glass, shields the lead-in 8 andanode 9 until it enters the cathode cylinder 3. An insulating glass beadl9 also surrounds the wire 9 at the other end of the cathode 3 to shieldit from high fields at that point. The helical spring it keeps the anodewire 9 taut.

In Figures 1. and 2, the silver coating 3 and the oxide 2 thereunder mayalso end a short distance from the end I?! if desired, but it preferablyextends to the end l2, which may be flanged over to fit a metal window3, which may be of a light metal such as aluminum or beryllium, of assmall a thickness as possible, for example t to 1 mil. The Window 13 maybe soldered directly to the silver coating on the glass. The coating ofother metal 3 may also extend to the end it if it is of a metal capableof being soldered. The solder used should be one which will withstandthe baking generally given the tube during the usual exhaust procedure.

In the tubes of Figures 1 and 2, the lead-in wire it may be of tungstenand may extend directly into the bulb coaxial with the coating 2, forexample, and be of sufficient diameter to be self supporting, with theinsulating bead I5 on its end to reduce the field at that point. Thetube iii should extend over the lead-in l4 near the end 5 for the samereason as in Figure 3. A second lead-in wire may be sealed into the bulband connected to cathode metal coatings 2, 3 in some suitable manner,for example by soldering, puddling, or by means of a split ring it whichexpands into connection with the cathode metal 2, 3 and is attached tothe lead-in wire it, at its beaded end.

If the wire Ill is too Weak for self support a supporting spider may exend from it to the coat ings 3, E, E3, the spider ccmprising radialwires broken by beads or the like for insulation.

If the coating 3 in Figure 2 is of silver, the coating 3 of bismuth anda coating It over that (shown broken away for convenience) of platinum,palladium, rhodium, iridium, chromium or chrome-iron, the tube will be acombined beta and gamma ray tube responding to either type of ray, andwill also resist the corrosive efiect of a halogen gas filling. Theadditional coating l8 may be omitted if halogen is not used.

The gas filling may be any of the usual mixtures, such as air with 98%neon, or may be a mixture of a rare gas and a halogen vapor such asbromine or chlorine, for example 26 cm. of mercury pressure of neon,with 0.8% argon and 0.2% chlorine. This is especially useful in the tubeof Figure 2, and gives a low voltage self quenching tube. The protectivelayers mentioned are useful with such a filling. With the thin windowsof Figures 1 and 2, the gas pressure must be fairly high approachinghalf an atmosphere or more, to prevent blowing the thin window in or outtoo much.

Mica may sometimes be used instead of metal for the window l3, and maybe affixed hermetically by means known in the art.

When a halogen gas filling is used, the anode wire 9 is preferably ofstainless steel rather than tungsten, because the stainless steelresists the corrosive effect of the halogen. The anode wire, if not of ametal suitable for sealing through the glass used in tube 5, may bespot-welded to a lead-in wire of suitable material, or may be beaded orotherwise arranged with several layers or tubes of glass to form agraded seal in the manner well known in the art.

The Word glass is used in a broad sense in this application, andincludes materials such as quartz and the like.

, What I claim is:

. l. A ray detection device comprising a glass tube, a gas fillingtherein, an anode therein, a firmly adherent coating of silver on theinside surface of said tube as a cathode, and a coating of bismuth overthe silver coating.

2. The device of claim 1, including a coating over the bismuth of ametal in the following group: chromium, platinum, palladium, rhodium,iridium.

3. The combination of claim 1, in which there is a thin bonding coatingof silver oxide between the silver coating and the glass.

4. The combination of claim 2, in which there is a thin bonding coatingof silver oxide between the silver coating and the glass.

5. A ray detection device comprising: a glass tube closed at one end andflared at the other; a firrn1y-adherent coating of silve on the insidesurface of said glass tube having a silver oxide bond to the glass andincluding a coated area over the flared end of the glass tube, and athin metal window transparent to beta rays and joined to the adherentsilver coating on to the flared portion of said tube; a gaseous fillingin said tube; and an anode in said tube.

6. A ray detection device comprising a glass tube closed at one end andflared at the other, a firmly adherent coating of silver on the insidesurfaceor" said glass tubeto act as a cathode, a coating of bismuth overthe silver coating, a thin window transparent to beta rays sealed to theflared portion of said tube, a gaseous filling in said tube, and ananode in said tube.

7. The combination of claim 6, a coating over the bismuth of one of thefollowing metals: chromium, platinum paladium, rhodium, iridium; and inwhich the gas filling includes a halogen.

8. The combination of claim 6, and a layer of silver oxid diffused intothe glass between the latter and the silver coating to act as afirmlyadherent bond therebetween.

9, The combination of claim 7, and a layer of silver oxide diffused intothe glass between the, latter and the silver coating to act as a firmlyiadherent bond therebetween.

10. A ray detection device including a glass tube, a gas fillingtherein, an, anode therein, a coating of silver bonded to the insidesurface of said tube by silver oxide, and a bismuth coating over thesilver coating.

11. A ray detection device comprising a glass tube closed at one end andflared at the other, a coating of silver on the inside surface of theglass tube to act as a cathode, a layer of silver oxide diffused intothe glass between the latter and the silver coating to act as, a firmlyadherent bond and between a thin window transparent to beta rays andsealed to the flared portion of said tube, a gaseous filling in saidtube, and an anode in said tube.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,884,665 Greiner Oct. 25, 19322,409,498 Keston Oct. 15, 1946 2,4423% Reid May 25, 19.48 2,475,603Friedman July 12, 1949 OTHER REFERENCES Liebson andFriedman: Review ofScientific Instruments, vol. 19, No. 5 of May 1948, pp.

